Hi,
Unless you really want a "retro" performance setup, I'd suggest a Mallory Unilite electronic dizzy instead.
The dual point *is* an improvement over the original, but today might be considered "old technology". For roughly the same cost you can get more improvement, easier servicing and less maintenance, and will have other ignition upgrade options with a Unilite. The Unilite and dual point don't look a lot different, externally. Either one can use certain of the upgraded Mallory coils (other coils are "points-only" or "electronic only").
But, if you ever want to add a multi-spark controller like the Mallory 6AL for whatever reason, with the dual point dizzy you'll end up disabling one of the sets of points in or converting it to electronic with a special Unilite module (an extra $110-120 expense). The Unilite is ready to add a multi-spark controller, if you wish.
As a rule of thumb, dual point is probably good up to 6000 rpm, a modest improvement over stock. Modified to work with a multi-spark controller it might be good to 8000 rpm. Unilite with certain electronic-only coils and a multispark controller might be good to over 10000 rpm. Now, it's unlikely you'll be revving your TR6 so high, but it gives you an idea of the increasing spark output and combustion strength produced by each level of improvement.
Another way to look at it is that the stock dizzy and coil probably calls for a .024" spark plug gap. Add a sport coil and you might be able to go to .025-.026" gap. With a dual point and a high output coil you might be able to increase that to .026-.028" for a stronger spark. With the Unilite, a multi-spark controller and electronic coil, it's possible .028-.032" gap could be used. All this is approximate and depends on other factors such as the plugs themselves, plug wires and how each individual engine is tuned in other respects. It is balanced off against using cooler plugs in high compression/high rev situations.
For my money, I'd choose the Unilite.
Mallory (at
www.mrgasket.com) has a lot of info online to help select ignition components that will "play well together".